Topic
Metaphase
About: Metaphase is a research topic. Over the lifetime, 6925 publications have been published within this topic receiving 291590 citations. The topic is also known as: GO:0007091 & mitotic metaphase/anaphase transition.
Papers published on a yearly basis
Papers
More filters
TL;DR: Xenopus oocytes microinjected with antibodies against the anaphase-promoting complex (APC) activator Fizzy or the APC core subunit Cdc27, or with the checkpoint protein Mad2 readily progress through the first meiotic cell cycle and arrest at second meiotic metaphase, but fail to segregate sister chromatids.
Abstract: Here we show that segregation of homologous chromosomes and that of sister chromatids are differentially regulated in Xenopus and possibly in other higher eukaryotes. Upon hormonal stimulation, Xenopus oocytes microinjected with antibodies against the anaphase-promoting complex (APC) activator Fizzy or the APC core subunit Cdc27, or with the checkpoint protein Mad2, a destruction-box peptide or methylated ubiquitin, readily progress through the first meiotic cell cycle and arrest at second meiotic metaphase. However, they fail to segregate sister chromatids and remain arrested at second meiotic metaphase when electrically stimulated or when treated with ionophore A34187, two treatments that mimic fertilization and readily induce chromatid segregation in control oocytes. Thus, APC is required for second meiotic anaphase but not for first meiotic anaphase.
139 citations
TL;DR: This work quantified the relationship between spindle elongation and cell size in the early embryo of Caenorhabditis elegans and proposed possible models for cell-size-dependent and Galpha-dependent modes of elongation.
138 citations
TL;DR: It is shown that ncd is important in maintaining spindle poles in mitosis as well as in meiosis, and a new mutant of ncd caused by partial deletion of the predicted coiled-coil central stalk is reported.
Abstract: Nonclaret disjunctional (ncd) is a kinesin-related microtubule motor protein required for meiotic and early mitotic chromosome distribution in Drosophila. ncd translocates on microtubules with the opposite polarity to kinesin, toward microtubule minus ends, and is associated with spindles in chromosome/spindle preparations. Here we report a new mutant of ncd caused by partial deletion of the predicted coiled-coil central stalk. The mutant protein exhibits a velocity of translocation and ability to generate torque in motility assays comparable to near full-length ncd, but only partially rescues a null mutant for chromosome mis-segregation. Antibody staining experiments show that the partial loss-of-function and null mutants cause centrosomal and spindle pole defects, including centrosome splitting and loss of centrosomes from spindle poles, and localize ncd to centrosomes as well as spindles of wild-type embryos. Association of ncd with spindles and centrosomes is microtubule- and cell cycle-dependent: inhibition of microtubule assembly with colchicine abolishes ncd staining and centrosomal staining is observed in prometaphase, metaphase and anaphase, but diminishes in late anaphase/telophase. The cell cycle dependence of centrosomal staining and the defects of mutants provide clear evidence for activity of the ncd motor protein near or at the spindle poles in mitosis. The ncd motor may interact with centrosomal microtubules and spindle fibers to attach centrosomes to spindle poles, and mediate poleward translocation (flux) of kinetochore fibers, a process that may underlie poleward movement of chromosomes in mitosis. Together with previous work, our findings indicate that ncd is important in maintaining spindle poles in mitosis as well as in meiosis.
138 citations
TL;DR: Mutations in the gene l(1)zw10 disrupt the accuracy of chromosome segregation in a variety of cell types during the course of Drosophila development, and Cytological analysis of mutant larval brain neuroblasts shows very high levels of aneuploid cells.
Abstract: Mutations in the gene l(1)zw10 disrupt the accuracy of chromosome segregation in a variety of cell types during the course of Drosophila development. Cytological analysis of mutant larval brain neuroblasts shows very high levels of aneuploid cells. Many anaphase figures are aberrant, the most frequent abnormality being the presence of lagging chromosomes that remain in the vicinity of the metaphase plate when the other chromosomes have migrated toward the spindle poles. Finally, the centromeric connection between sister chromatids in mutant neuroblasts treated with colchicine often appears to be broken, in contrast with similarly treated control neuroblasts. The 85-kD protein encoded by the l(1)zw10 locus displays a dynamic pattern of localization in the course of the embryonic cell cycle. It is excluded from the nuclei during interphase, but migrates into the nuclear zone during prometaphase. At metaphase, the zw10 antigen is found in a novel filamentous structure that may be specifically associated with kinetochore microtubules. Upon anaphase onset, there is an extremely rapid redistribution of the zw10 protein to a location at or near the kinetochores of the separating chromosomes.
138 citations
Journal Article•
TL;DR: The fine structure of nuclear division in late syncytial embryos is examined and the factors that affect the integrity of PCs in dividing blastoderm nuclei appear to affect those in other membrane systems to an equivalent degree and with identical timing.
138 citations